Orthoses and osteoarthritis: what we should know

Osteoarthritis is a chronic joint impairment progressively leading to cartilage destruction, characterised by pain when walking or performing a physical activity and eased with rest.

One existing therapeutic treatment approach (mainly for lower limb osteoarthritis) is the prescription of mechanical supports, called orthoses, intended to compensate and assist the deficient joint function. These devices are recommended, in particular, by the European League Against Rheumatism (EULAR)1 and the American College of Rheumatology (ACR)2 in the non-pharmacological treatment of knee osteoarthritis. Three types of orthoses are available for knees and ankles:

- Resting orthoses. These orthoses, made from a rigid component, immobilise the joint, thus excluding any corrective or functional effects. They are rarely prescribed in cases of lower limb osteoarthritis (7 to 10% of cases) and their efficacy has not been established.

- Flexible orthoses. Contrary to resting orthoses, these are elastic and non-adhesive, allowing their use with other devices. Between one quarter and one third of practitioners prescribe them frequently in cases of knee osteoarthritis. Studies have demonstrated that their use reduces pain and enhances short-term subjective improvement, though they do not provide any improvement in functional capacity3, 4.

- Articulated orthoses. These are functional devices consisting of external rods and hinges. Their efficacy has not been clearly established, even though it would appear that they reduce compressive loads transmitted to the joint surfaces in the context of internal femorotibial osteoarthritis5, 6, 7. According to some studies, they also appear to improve knee proprioception, vertical propulsion force8 and step symmetry9. Despite this, they their prescription rate remains low (23% of physicians systematically propose them, along with only 9% of rheumatologists), mainly because they have been associated with a range of side effects10, 11.

Foot orthoses, inserted into a shoe, or strapped on, are also available. These are routinely prescribed, in particular for knee osteoarthritis, though no specific recommendations have ever been made (type of orthosis, time worn, recipients) and most studies have concluded that their efficacy is limited12, or even non-existent13, 14. The theories put forward for modelling the action of these orthoses are precise, though they are based on insufficiently validated biomechanical concepts15.